Basically my idea is a program that'll graph trends in the item market (not the board) based on prices of particular items (right foot texture, viridian relax, etc), particular colours (vampire, marine, etc) and particular colour groups (red, green, blue, etc). (APPARENTLY THE SAME THING AS RUNESCAPE GRAND EXCHANGE GRAPHS)

The graphs will show minimum + maximum prices and changes in prices over a particular amount of time (probably about a month variable), checked + generated daily or however often I think is necessary.

SUGGESTED AND APPROVED:
- Direct comparison between items/groups on a single graph (will be interesting to see what sort of price correlations come up :D)

Any suggestions as to (more) cool features I could integrate, before I get started?

AN EXAMPLE GRAPH:

I have no suggestions for now

But you should include the basics of the market

Item Popularity
Prices Drop
Prices Raise

Edit:
This will give you some ideas
http://stockcharts.com/

I hate you for ruining my 2^n postcount. >:(

But really: Item popularity will be hard unless the market is updated to include a "recent sales of item X" page (unlikely). Prices dropping/rising come under "changes in prices," which is mentioned in my first post.

Something like the Runescape grand exchange graphs?
A feature to select what timespan to see changes in would be useful. You could see trends over a year and see how they change at each restock.

After a quick google (I've never played runescape) yes. That's almost exactly what I've got in mind, but I probably won't make it a webpage because I'm getting sick of that sort of thing.
Edit:
(22:40:24) <lsl> If/when I get it working properly I'll integrate it into a site somehow, but to start with I'd like to generate stats for myself
(22:40:40) <lsl> more out of personal interest than anything else
(22:40:58) <lsl> I'm just asking for a few ideas for when I do make it public
(22:41:09) <lsl> should probably state that explicitly

Adding variable domain to feature list

Further edit:
(22:41:56) <Gum> I honestly cant think of anything you haven't listed. Maybe a comparison tool for different colors. Like say I want to compare the prices for vampire and supernova over a month, have the 2 show up in a line graph as separate lines on the same graph
/me slaps self.
/me adds to feature list.

Well, it looks like shit at the moment, but it's almost done. All I need to do is set up automatic fuckingoff of ridiculous outliers (search the market for aqua blood for an example), a cron job to generate the right graph files and another to generate the actual graphs (as well as some tweaking to the actual graph generation process).

The finished graphs will look something like this (except with labeled axes and, in the case of multiple sets of data, a key):

Ixor: looks quite cool. Do you have an own charting-class or are you using an external one like phpchart/fusion?

If you want I can give your tool a place on the ToriNet-page then. Or at a subdomain there

LXOR D:<

Also, answered your question on IRC but I'll put the answer here for anyone who's curious: (00:52:03) <+lsl> I'm using PHP to get + properly format the stats and C to pipe it all into gnuplot and generate images
I'll be using cron to automate the whole process and set it up to run at midnight every day, and then I'll think about what I'm going to do with all the data. :3

how does the grapher get this information?
if its of auto market system thingy then it might be skewed for certain items.

For example crimson lax was 8k a couple of weaks ago.
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anyway looks lieka great market accessary

That wouldn't really be a bad thing. The entire point of this is to display in a simple manner the changes in price of an item -- that's one of the cases in which the graphs would have been helpful. You could have, very easily, seen the lowest price of crimson relaxes rising and thought "well, if I buy a bunch now I can sell them when the price maxes out and get a load of TC. :O!" and proceeded to do that.

How it gets the information is irrelevant! (But really it logs in to the forums and then downloads a bunch of pages from the market from which it extracts price data.)
And thanks! :3